1. Technical Field
This invention relates to the field of providing call handoff in a wireless environment such as a neighborhood cordless service that provides service at a flat rate wherein there is no air time charge for calls made within a home neighborhood zone or subscribed-to visiting neighborhood zone(s).
2. Description of the Related Arts
It is known to provide wireless services for a fixed fee and to charge additional air time fees for each period of time that a subscriber to the wireless services is using :the radio frequency spectrum. Such services were initiated in the 1970""s as analog wireless services and have become digital over time, for example, the relatively new digital personal communications services (DPCS).
It has been known up until recently to permit users to have cordless telephone apparatus comprising a base station and a mobile unit such that the mobile unit may communicate with the base station over limited distances of several hundred feet. Recently, in the United States, however, a band of frequencies has been made available in the 900 MHZ range for providing cordless telephone service where the mobile station can be as far removed from the base station portion of the station apparatus by as much as one mile under optimal conditions. Consequently, a user would not have to pay for air time charges as in wireless services such as personal communications services if a mobile station is confined within one mile radius of the typically home-located base station.
Fixed wireless subscriber loop services are also known. Equipment for providing such services is available from suppliers such as Diva Communications and OptoPhone Systems. The fixed wireless subscriber loop concept has been used successfully to provide telephone services to remote, for example, mountainous regions. To provide a copper wire subscriber loop to such customers can cost hundreds of thousands of dollars per subscriber. Subscribers to a fixed wireless subscriber loop system have an antenna mounted to their home or business and receive an equivalent of wired services over a wireless link to an antenna site, for example, on the top of the mountain. Service can be provided for a fixed rate, the copper subscriber wired loop eliminated and no air time charges are charged.
There is still a need in the art for a wireless service that would permit a mobile subscriber to roam within a zone close to their home in the same way as a 900 MHZ cordless customer is free to carry their cordless phone from room to room. A mobile subscriber should be able to roam and also move from one zone to another or make calls from non-contiguous zones without having to pay for air time charges. In today""s cellular environment, airtime is charged. The current fee structure thus has very little incentive for customers to continue use their cellular phones when they have access to a home-based landline phone. In order to achieve the objectives of one phone, one number anytime and anywhere communications, it is imperative that a neighborhood or local xe2x80x98cordless typexe2x80x99 of services be provided to all the public cellular/PCS subscribers and with incentive to use the same PCS phone in the home/office and around the neighborhood area without air time charges. A subscriber should not lose a call in progress as they move from one subscribed-to zone to another adjacent subscribed zone, and should have the opportunity to switch automatically to known DPCS services and pay air time charges should they so choose.
There is further a need for providing call hand-off in such a proposed wireless service. For example, there is a need to provide call hand-off between cells in such a proposed network and at between such a proposed network and an existing conventional network such as a conventional macro-cellular wireless network.
Subscribers to a local cordless service according to the present invention may subscribe to a home neighborhood zone and optionally one or more visiting neighborhood zones from which the subscribers may place telephone calls without having to pay air time charges. By local cordless service is intended a mobile wireless subscriber loop service wherein stations are mobile and the subscriber loop to the customer""s premises may be replaced with a wireless loop. The subscriber need not maintain their wired connection to a local exchange carrier (LEC). If the subscribers are current public digital PCS service users, they may use their existing cellular phone and unique mobile identification number (MIN) for subscription to the service. Subscribers may also have the option of electing new wireline numbers to be assigned to their cellular phone for subscription of the service and the numbers assigned may be the traditional PSTN 100 directory number (DN). Alternatively, the subscribers can elect to port their existing wireline DNs to this service. If the subscriber is not a public cellular user, they will need a cellular phone or other mobile station (MS) assigned with either a new DN or their ported DN from the incumbent local exchange carrier (ILEC).
According to one embodiment of the present invention, a subscriber to such a mobile service pays a flat rate that is competitive with or even less expensive than a subscriber to conventional wired public switched telecommunications services. In their home zone, which may be approximately the same size as, or even slightly larger in size than, the range of a standard 900 MHZ cordless phone, the subscriber may carry or otherwise receive services at one flat rate (regardless of air time used). For additional flat fees, the subscriber may also make calls in one or more visited zones which may be contiguous with or remote from the home zone.
When a subscriber travels between the subscribed home zone and an adjacent visiting zone or between adjacent visiting zones, the call may be handed off to the other zone without interruption to the call in progress. Also, when a subscriber moves from any subscribed zone to a public cellular/PCS environment, the call may be handed off without air time charges for the duration of the same call.
As a subscriber leaves their home zone and roams toward a remote (i.e., non-adjacent) visited zone, there exist at least three alternative ways of billing a call in progress. In one embodiment, the call in progress will be terminated when the boundaries of the subscribed-to zone are reached. In another embodiment, the call will be allowed to continue without air time charges for a predetermined period of time as a public cellular carrier (e.g., a conventional digital personal communications service call). In this invention the preferred method is to allow the call to continue but the subscriber will be switched over to public cellular carrier frequency without air-time charges for the duration of the same call
Thus, aspects of the present invention describe a method comprising the step of handing off a telephone call involving a mobile station between a first subscribed zone of a local cordless service to a macro-cellular service different from the local cordless service. More specifically, aspects of the invention involve a method comprising the step of handing off a telephone call involving a mobile station between a first subscribed zone of a mobile wireless subscriber loop service to a different wireless cellular service, the first subscribed zone being associated with a mobile station, wherein an amount that is billed toward use of the mobile station is not affected by an amount of airtime used by the mobile station within the first subscribed zone.
Further aspects of the present invention describe a first wireless network configured to communicate with a mobile station and to communicate with a second wireless cellular network, the first wireless network comprising: a first radio transmitter providing a mobile wireless subscriber loop service having a first subscribed zone, the first radio transmitter serving the first subscribed zone associated with the mobile station, a telephone call being in progress involving the mobile station within the first subscribed zone, wherein an amount that is billed toward use of the mobile station is not affected by an amount of airtime used by the mobile station within the subscribed zone; and a switch connected to both the first wireless network and the second wireless cellular network, the switch being configured to assist in handing off a telephone call involving the mobile station to the second wireless cellular network.
These and other features of the present invention will be understood from studying the drawings and the following detailed description of various embodiments.